The producers of the Rocky Horror Show have apologised for their handling of sexual misconduct claims against star Craig McLachlan, after more cast members came forward with claims about bullying and intimidation.

Key points:

Two more people have come forward with claims of inappropriate behaviour

Production company's boss "sincerely apologises" to the women at the centre of the original allegations

Wednesday's apology from Gordon Frost Organisation (GFO) managing director John Frost was issued after the ABC and Fairfax approached the company with questions about two cast members who allege a GFO manager ignored their complaints about bullying.

The former cast members, who asked not to be identified, spoke out after GFO denied ever receiving complaints "formal or informal" about star Craig McLachlan's behaviour during the show's 2014 run.

That denial was issued after a joint ABC-Fairfax investigation revealed allegations by three of McLachlan's female co-stars, who claimed he indecently assaulted, sexually harassed and bullied them.

McLachlan has strenuously denied those allegations against him, describing them as baseless, vicious and outrageous.

The three women said they complained at the time but nothing was done to protect them.

After being approached about the latest allegations on Wednesday, GFO managing director John Frost issued a statement apologising to the three women — Erika Heynatz, Christie Whelan Browne and Angela Scundi — who made the original claims.

On Wednesday, while stressing that the women had not made a formal complaint, Mr Frost said he had "no reason to disbelieve anyone who says they spoke to one of our managers in 2014".

"However, none of our managers were aware of any issues that warranted further action at the time, and all of our employees were aware of the procedures of making a complaint," he said.

"I'd also like to say to Christie, who said she spoke to me personally backstage and told me that she was frightened of Craig, that I can honestly say while I remember seeing her briefly, I cannot remember any discussion around Craig.

"I can only explain this by pointing out that I speak to many people backstage across many productions and have little time to spend with each person."

Mr Frost also addressed the women's claims that GFO had threatened to sue them for defamation after lawyers acting for the trio sent an email with a list of complaints against McLachlan.

"While the letter we received contained some of the alleged allegations, it is impossible to conduct any sort of investigation when the names of those making the allegations are not given nor specific details," he said.

"The anonymous nature of their letter also indicated other possible motives."